Obesity linked to longer survival in men with advanced melanoma

BY
Scott Merville

Obese patients with metastatic melanoma who are treated with targeted or immune therapies live significantly longer than those with a normal body mass index (BMI), investigators report in a study published in Lancet Oncology of 1,918 patients in six independent clinical cohorts.

This effect, referred to as the “Obesity Paradox”, principally manifested itself in men, said Jennifer McQuade, M.D., lead author and instructor of Melanoma Medical Oncology at MD Anderson.

“Obese men consistently did much better than men with a normal BMI, with nearly a doubling of overall survival,” McQuade said. The researchers found no significant differences in survival between women with normal, overweight or obese BMI.

“The question is what underlying mechanism causes this advantage in obese men, and can we take advantage of it to improve outcomes in patients with melanoma?” McQuade said. “One hint may be the interaction between obesity, sex, and outcomes, which has not been detected before in any cancer.”

Women with metastatic melanoma have long been known to have better outcomes compared to men, McQuade noted. In this study obesity overcame that survival disadvantage for men, leading researchers to now look at the possible impact of sex hormones in this effect.

Associations don’t prove causation, the researcher’s note, but point to new areas to study in greater depth.

“The public health message is not that obesity is good. Obesity is a proven risk factor for many diseases,” McQuade said. “Even within our metastatic melanoma population, we would not suggest that patients intentionally gain weight. We need to figure out what is driving this paradox and learn how to use this information to benefit all of our patients.”

Obesity is a known risk factor for developing 13 types of cancer according to the World Health Organization and is set to overtake smoking as the leading preventable cause of cancer. The relationship between obesity and survival in patients that already have cancer is not as consistent. Recent studies have shown a similar survival benefit for obese patients with colorectal or kidney cancer.